21、Java加密技术（三）——PBE算法

<转>http://snowolf.iteye.com/blog/380761
PBE
    PBE——Password-based encryption（基于密码加密）。其特点在于口令由用户自己掌管，不借助任何物理媒体；采用随机数（这里我们叫做盐）杂凑多重加密等方法保证数据的安全性。是一种简便的加密方式。

package org.nick.encrypt;
import java.security.Key;  
import java.util.Random;  
import javax.crypto.Cipher;  
import javax.crypto.SecretKey;  
import javax.crypto.SecretKeyFactory;  
import javax.crypto.spec.PBEKeySpec;  
import javax.crypto.spec.PBEParameterSpec;   
/** 
 * PBE安全编码组件 
 * @version 1.0 
 * @since 1.0 
 */  
public abstract class PBECoder extends Coder {  
    /** 
     * 支持以下任意一种算法 
     *  
     * <pre> 
     * PBEWithMD5AndDES  
     * PBEWithMD5AndTripleDES  
     * PBEWithSHA1AndDESede 
     * PBEWithSHA1AndRC2_40 
     * </pre> 
     */  
    public static final String ALGORITHM = "PBEWITHMD5andDES";  
  
    /** 
     * 盐初始化 
     *  
     * @return 
     * @throws Exception 
     */  
    public static byte[] initSalt() throws Exception {  
        byte[] salt = new byte[8];  
        Random random = new Random();  
        random.nextBytes(salt);  
        return salt;  
    }  
  
    /** 
     * 转换密钥<br> 
     *  
     * @param password 
     * @return 
     * @throws Exception 
     */  
    private static Key toKey(String password) throws Exception {  
        PBEKeySpec keySpec = new PBEKeySpec(password.toCharArray());  
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);  
        SecretKey secretKey = keyFactory.generateSecret(keySpec);  
  
        return secretKey;  
    }  
  
    /** 
     * 加密 
     *  
     * @param data 
     *            数据 
     * @param password 
     *            密码 
     * @param salt 
     *            盐 
     * @return 
     * @throws Exception 
     */  
    public static byte[] encrypt(byte[] data, String password, byte[] salt)  
            throws Exception {  
  
        Key key = toKey(password);  
  
        PBEParameterSpec paramSpec = new PBEParameterSpec(salt, 100);  
        Cipher cipher = Cipher.getInstance(ALGORITHM);  
        cipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);  
  
        return cipher.doFinal(data);  
  
    }  
  
    /** 
     * 解密 
     *  
     * @param data 
     *            数据 
     * @param password 
     *            密码 
     * @param salt 
     *            盐 
     * @return 
     * @throws Exception 
     */  
    public static byte[] decrypt(byte[] data, String password, byte[] salt)  
            throws Exception {  
  
        Key key = toKey(password);  
  
        PBEParameterSpec paramSpec = new PBEParameterSpec(salt, 100);  
        Cipher cipher = Cipher.getInstance(ALGORITHM);  
        cipher.init(Cipher.DECRYPT_MODE, key, paramSpec);  
  
        return cipher.doFinal(data);  
  
    }  
}  

import java.math.BigInteger;
import org.nick.encrypt.Coder;
import org.nick.encrypt.DESCoder;
import org.nick.encrypt.PBECoder;
public class Test
{
    public static void main(String[] str) throws Exception {  
    	String inputStr = "PBEWITHMD5andDES";  
        System.err.println("原文: " + inputStr);  
        byte[] input = inputStr.getBytes();  
  
        String pwd = "efg";  
        System.err.println("密码: " + pwd);  
  
        byte[] salt = PBECoder.initSalt();  
  
        byte[] data = PBECoder.encrypt(input, pwd, salt);  
  
        System.err.println("加密后: " + PBECoder.encryptBASE64(data));  
  
        byte[] output = PBECoder.decrypt(data, pwd, salt);  
        String outputStr = new String(output);  
  
        System.err.println("解密后: " + outputStr);  
  
    }  
}

原文: PBEWITHMD5andDES
密码: efg
加密后: uaHJ83fFo1lbfSvX4oBD5BdJMsM+Mq+F
解密后: PBEWITHMD5andDES